1. Field of the Invention
The present invention relates to an ink-jet printhead in which, by expanding and contracting motions of piezoelectric transducing elements of the longitudinal vibration mode, ink drops are ejected through discharge orifices onto a printing medium to print images, characters and the like thereon. More particularly, the invention relates to a flexible cable for supplying drive signals to a transducer unit having a plural number of piezoelectric transducing elements being arrayed at fixed pitches and fixed onto a fixing plate.
2. Background
Compared with other ink-jet printheads, the printhead which operates in the longitudinal vibration mode is able to operate at a relatively high frequency. In this printhead, a discharge orifice and an elastic plate, constituting parts of a pressure generating chamber, are in fluid communication with a reservoir and form an ink ejecting means. A transducer unit is made up of a plural number of piezoelectric transducing elements of the longitudinal vibration mode, which are arrayed at fixed pitches and fixed on a fixing plate. This type of the piezoelectric transducing element vibrates, or repeats alternating expanding and contracting motions in its longitudinal direction.
A flexible cable is connected to the transducer unit of this type for applying drive signals from an external drive circuit to the piezoelectric transducing elements of the transducer unit. A conventional connection of the flexible cable to the transducer unit is as shown in FIG. 11. Connection patterns A are formed on and along the leading end of a flexible cable B, while being arrayed therealong at a pitch corresponding to the pitch of the transducing element array (FIG. 11(a)). To connect the flexible cable B to a transducer unit C, the connection patterns A of the flexible cable B, respectively, are aligned with and bonded, by soldering, to the connection terminals E of piezoelectric transducing elements D of the transducer unit C, respectively (FIG. 11(b)).
Specifically, to connect the flexible cable B to the transducer unit C, the connection patterns A of the flexible cable B are vertically roughly aligned with the connection terminals E of the piezoelectric transducing elements D, respectively. The operator, while observing by, for example, a magnifier, slides the flexible cable B above and along the surfaces of the piezoelectric transducing elements D and exactly aligns the connection patterns A respectively at the connection terminals E, and solders the former to the latter.
To secure an easy connection, solder layers are formed on the connection patterns A while being slightly raised from the surface of the flexible cable B. To prevent the shortcircuiting by the molten solder, the width of the connection patterns A 15 shorter than that of the width of the piezoelectric transducing elements D. When aligning the connection patterns A with the connection terminals E of the piezoelectric transducing elements D, the connection patterns A may be positioned in the space between the adjacent piezoelectric transducing elements D as shown in FIG. 11(c). In this state, if the flexible cable B is moved with respect to the transducer unit C for positioning, the connection patterns A of the flexible cable B forcibly hit the edges of the piezoelectric transducing elements D to possibly damage the latter. In an extreme case, the piezoelectric transducing elements D are broken at the edges to reduce the connection areas thereof, creating poor contact problem.
Accordingly, an object of the present invention is to provide a flexible cable in use with the transducer unit of the longitudinal vibration mode, the flexible cable being reliably connected to the transducer unit without damaging the transducer unit.